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<html>

<head>
	<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
	<title>导航栏</title>
  <style>
    ul {
      /* 不需要指示器和边距 */
      list-style-type: none;
      margin: 0;
      padding: 0;
      width: 25%;
      height: 100%;
      position: fixed;
      overflow: auto;
      background-color: #f1f1f1;
    }
    li a {
      display: block;
      color: #000;
      padding: 8px 16px;
      text-decoration: none;
    }
    li a:hover {
      background-color: #555;
      color: white;
    }
    .active {
      background-color: #4CAF50;
      color: white;
    }
  </style>
</head>

<body>
<ul>
  <li><a class="active" href="#home">主页</a></li>
  <li><a href="#news">新闻</a></li>
  <li><a href="#contact">联系</a></li>
  <li><a href="#about">关于</a></li>
</ul>

<div style="margin-left:25%;padding:1px 16px;height:1000px;">
  <h2>Fixed Full-height Side Nav</h2>
  <h3>Try to scroll this area, and see how the sidenav sticks to the page</h3>
  <p>Notice that this div element has a left margin of 25%. This is because the side navigation is set to 25% width. If you remove the margin, the sidenav will overlay/sit on top of this div.</p>
  <p>Also notice that we have set overflow:auto to sidenav. This will add a scrollbar when the sidenav is too long (for example if it has over 50 links inside of it).</p>
  <p>Some text..</p>
  <p>Some text..</p>
  <p>Some text..</p>
  <p>Some text..</p>
  <p>Some text..</p>
  <p>Some text..</p>
  <p>Some text..</p>
</div>
</body>

</html>